Posted by **Adam** on Tuesday, August 2, 2011 at 8:51pm.

River Current A boat can travel 36 miles upstream in the same time that it can travel 54 miles downstream. If the speed of the current is 3 miles per hour, find the speed of the boat without a current.

- math -
**Reiny**, Tuesday, August 2, 2011 at 10:36pm
let speed of boat in still water be x mph

upstream:

speed = x-5

time = 36/(x-5)

downstream:

speed = x+5

time = 54/(x+5)

the two times are equal, so

36/(x-5) = 54(x+5)

54x - 270 = 36x + 180

18x = 450

x = 25

The speed of the boat without a current is 25 mph

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**kayla garner**, Monday, February 4, 2013 at 12:54pm
A canoe can travel 18 mph in still water and 22 miles downstream in the same amount of time that it takes to travel 14 mph upstream. Find the speed of the current in the water.

- math -
**Megan**, Tuesday, March 12, 2013 at 1:17am
a person can copy the final exam in 28 minutes using a new copy machine. using an old copy machine, it takes 70 minutes. if both machines are used, how long will it take to complete the job

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